Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


PCB Cleaning

#29437

PCB Cleaning | 8 July, 2004

Hello,

I have been tasked with updating our PCB cleaning sytem, of which I know little about, and could really use some advice. We are a small company and we hand solder our electronics to IPC standards. Our electronics are mission critial communication systems for military so very high levels of cleanliness are required which we currently do not have. Our PCB assemblies are a mixture of SMT and discrete.

I am trying to keep cost down while meeting the high standards for cleanliness and low ionization.

If anyone would recommend a process I would be forever in your debt.

Thanks You, wa engineer

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Chris Lampron

#29439

PCB Cleaning | 9 July, 2004

WA Engineer,

Good Morning, Your cleaning system requirements will depend on your chemistry use in production. Are you using RMA or OA flux? This will impact the requirements of the cleaning system. OA will allow you to use a DI water cleaner. If you use RMA, a DI with saponifier or IPA wash may be required. What are your typical batch sizes? Smaller batch sizes lend themselves well to batch style cleaners (dishwashers) where higher volumes may require an inline system. There are many options available. They would really depend on your specific requirements.

I Hope This Helps

Regards

Chris

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#29445

PCB Cleaning | 9 July, 2004

Hi Chris,

We use RMA but are considering changing to OA if it will help us acheive our goals of high quality and low cost. Our boards are requred to meet IPC class 3. Again, I am new to this so any advice about flux is appreciated. We are currently outsourcing the boards and as I have heard the company uses some kind of dishwasher technique. One concern of mine is what to do with the wastewater. How do you dispose the dirty DI water and how often? Our max batch size is roughly 25 boards.

The dishwasher technique is very interesting. Do you know where I can find out more about it?

Thanks again,

wa engineer

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Chris Lampron

#29447

PCB Cleaning | 9 July, 2004

WA Engineer,

If you are able to change over to OA instead of RMA, you can clean effectively with DI water. (I know that some Military contracts specify RMA) Most systems are designed to filter the waste water of ionized contaminants before dumping to drain. Other systems use a closed loop DI track (this is what we use) that recycles the water to use over. There are many companies that make DI dishwasher style cleaners. Aquious Technologies is the first one that comes to mind. We have used Separation Technologist and US Filters for our DI filtering. If you have to use RMA, a water wash with a saponifier such as Kyzen Aquanox works well.

Hope This Helps

Regards

Chris

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#29448

PCB Cleaning | 9 July, 2004

This is a shot in the dark for you. On some of our low running boards (5 pieace). Instead of turning the wash on the operators will use a good ole steam cleaner. We used DI water in this process. The main reason we started using this in the first place is medical equipment and they wanted it totally sprayed and they seemed to like the outcome. Hopefully this helps in some sort of matter.

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#29449

PCB Cleaning | 9 July, 2004

It looks like our max batch size will be 50 boards (approx 5" x 3") and we will run 1 per day. I am researching the contract for references to using only RMA flux. I don't think there are any. It is starting to look like the OA with DI diswasher is the way to go. Thanks for your help. I am sure I will be back with more questions.

wa engineer

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Mike Konrad

#29451

PCB Cleaning | 9 July, 2004

The following link discusses the advantages and disadvantages of batch and inline cleaning equipment. The validity of each technology is determined by your unique / specific application.

http://www.aqueoustech.com/Q_A_Batch_Inline.htm

Batch machines are available in both low discharge and zero discharge configurations.

Mike Konrad Aqueous Technologies www.aqueoustech.com (909) 944-7771 ext 29

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#29473

PCB Cleaning | 13 July, 2004

Cleaning RMA fluxes simply requires selecting a washing chemistry (either Solvent, Semi-aqueous or Aqueous) and an appropriate cleaning sytem. Your lot size would be easily handled with a batch system.

visit http://www.aat-corp.com/Technical/Default.htm to read about a 5 Step Approach to A successful cleaning process.

For semi-aqueous and aqueous mixtures, the DI rinse solution can be recycled which virtually eliminates concerns for rinse water discharge. However, the wash solution will need to be occasionally discharged. Several ways to do this including containing and treating as hazardous material, evaporation, and in some cases municipalities will accept a moderate, non-continuous discharge. Alternatively, a solvent wash and solvent rinse (no DI water required) will work with zero discharge capabilities. The solvent is filtered and recharged for continuous re-use.

You should consider that converting from RMA to OA will require several processes changes, including printing charactoristics and reflow profiles. Also, Rosin Mildly Activated (RMA) fluxes are typically more common in Military applications than Organic Acid fluxes. If the specification does not call out the type of flux, a final confirmation from the customer may prove more advantageous.

Hope this is useful information for you and your company.

Shean R. Dalton Austin American Technology www.aat-corp.com (512) 335-6400 ext. 20

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Jarmato

#29499

PCB Cleaning | 14 July, 2004

You may also want to investigate an Ionic contamination tester. You can check with Alpha, Westek or an equipment broker to find a used tester. If you switch to OA fluxes this will be an important test to perform on a regular basis.

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PCB Cleaning

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